Gas furnace sometimes doesn't light. [gas furnace]

I've got a gas furnace that's about 23 years old. I know replacing it would be a fix but it's been rock solid and I've had it serviced recently. They put a machine on it to check for cracks and it checked out ok. That was about 6 months ago.

Right now when heat is requested I can see the igniter start to glow and *most* of the time the furnace starts right up but some times gas flows but there is no actual ignition. If I blow through the furnace grates it'll light right off.

I also have a steam humidifier that sometimes seems to get WAY too aggressive and floods the duct work. I suspect it's because the heater has not "lit" a few times and has gone into a safe mode so when the humidifier calls for the fan nothing happens. When it's in this state i have to power cycle the whole thing.

I think If I solve the "needs a blow through the grates to light" issue it'll all be fine. Could i maybe have cobwebs in the "burner" ports or something? I could blow that area out with compressed air but I want some advice before doing anything.